Reforestation is often carried out by outplanting seedlings that have been grown in seedling nurseries. The seedlings may be bare root stock or, more commonly, the root is enveloped in growth medium in the form of a plug in a containerxe2x80x94this latter is referred to as containerized stock. Outplanting of containerized stock, therefore, involves placing the plug into soil at the reforestation site.
For the purposes of this specification, the term xe2x80x9cplugxe2x80x9d will be considered to include pelletsxe2x80x94for example, Jiffy(trademark) pelletsxe2x80x94and any other suitably retained growth medium, for example, growth medium in multiple cavity containers such as styroblocks. A number of plugs are typically retained in a block. For the purposes of this specification, the term block will, therefore, refer to any container that has a plurality of cavities each which holds a plug. Further, the term xe2x80x9cfertilizerxe2x80x9d will be considered to include both organic and inorganic forms of fertilizer.
To produce containerized stock, the seedlings are seeded directly into the plug, which has been prepared in advance, by filling a plug cavity with a growth medium. Typically, the growth medium is inert and is, for example, comprised of peat or a mixture of peat, vermiculite and sand. As the medium is very low in plant nutrients, fertilizer is provided either as a slow-release fertilizer that is included in the mix, or through fertigation.
Commonly, slow-release fertilizers are available as prills. In this context, xe2x80x9cprillxe2x80x9d is encapsulated fertilizer in the form of a bead. A prill in the context of conifer seedlings growth is chemical or organic fertilizer encased in a polymeric coating made of plastic. Alternatively, granular formulations, both organic and inorganic, may be used that slowly release the fertilizer. These slow-release fertilizers may be added to the plug at the time of sowing with the objective of providing a residual load to the seedling once it is lifted and outplanted. However, regardless of the type of slow-release fertilizer used, much of it has been expended by the time the seedling is ready to be lifted.
Once a seedling reaches the prescribed height, caliper and developmental stage, it is lifted. At this time, it may be outplanted directly, as occurs with the xe2x80x9chot liftxe2x80x9d seedlings, or it may be placed in cold storage, where it will remain over the winter. At the end of the cold storage period, the seedling is thawed and outplanted directly into the reforestation site.
Establishment of the seedling in the reforestation site is a critical step in the reforestation process. Hence there has been research on methods of increasing the rate of early growth. Frequently, seedling growth following outplanting is limited by a lack of adequate nutrients.
Research to increase the availability of nutrients to the seedling following outplanting has been extensive and has focussed on such techniques as co-cultivating mycorhizal fungi with the seedling roots in the nursery, placing fertilizer xe2x80x9ctea bagsxe2x80x9d in a hole next to the hole that the plug is planted into at the reforestation site (U.S. Pat. Nos. 5,022,182 and 5,317,834), and studying root growth to determine ways to increase the seedling""s access to the limited soil nutrients. Limited fertilizer spray programs have also been implemented, but unfortunately, these often result in the brush and weeds outgrowing the seedlings. When this occurs, the brush and weeds have to be controlled, adding further expense to the cost of reforestation.
Despite the concern about the availability of nutrients to the seedling following outplanting, fertilization at lift, rather than at or following outplanting, does not appear to have been actively pursued. Hence the prior art for such an approach appears to be limited to field crop fertilizers, crop seeders and the lifting and packaging equipment currently employed in seedling nurseries.
There are many patents that disclose devices and methods for injecting materials, including fertilizer into soil. These have been developed for field crops, and not for containerized crops, such as conifer seedlings. For example, U.S. Pat. No. 5,394,812 discloses a device and method to inject polymeric materials into soil. The invention is based on a fluid delivery system, with pumps and monitors to control the flow rate. The monitor is in the form of a float valve. The fluid with the polymer therein is delivered to a series of apertures by means of a high pressure pulse.
U.S. Pat. No. 4,907,516 discloses a device and method for pulsed injection of liquid fertilizer into the soil. A solenoid control valve operates intermittently to interrupt the flow of liquid in order to provide liquid fertilizer to the nozzle in a series of short pulses. Penetration of the fertilizer into the soil is dependent upon the force of the jet of liquid through the nozzle.
Seeders for various purposes are previously known. U.S. Pat. No. 6,237,514 discloses an apparatus and method for disbursing agriculture seeds and other particulate materials into soil. A hopper supplies seeds to pockets that are located on sprocket wheels. The seeds are retained in the pocket by a housing that abuts the sprocket wheels. The number of seeds that are retained in each pocket is dependent upon the seed size and the pocket size. Rotation of the sprocket wheels to an open position in the housing results in release of the seeds. The seeds drop without assistance and land on the soil. Seed bed preparation therefore is carried out separately prior to seeding.
U.S. Pat. No. 6,273,648 discloses apparatus providing even distribution of air-entrained particulate material to headers and ultimately to delivery nozzles. Specifically, the patent discloses a conveyor tube and distribution header for use with pneumatic seeders. Turbulence is used within the conveyer tube to propel the seeds toward the distribution head. The distribution head receives the seeds through a flow inlet and then divides the flow into a number of outlet ports.
Another apparatus for dispensing granular or particulate materials is disclosed in U.S. Pat. No. 5,189,965. The apparatus is designed to uniformly discharge a predetermined quantity of granular material at a predetermined rate of application. A hopper is used to feed a metering system that has a number of rollers with pockets to receive the granular material. As the rollers turn, the granular materials are released into segregated metering channels and are pneumatically propelled through a delivery system. Hence, a continuous stream of granular or particulate materials is dispensed onto the soil.
The nursery industry employs mechanized planters for emblings (somatic embryos) and seeds. Essentially, a dibbler is used to create a depression in the seed bed and seeds or emblyings are dropped into the depression. The seed bed may be a transplant bed. Alternatively, the seeds may be sown directly into the plugs. The plugs are arranged in a block such as a styroblock.
Typical styroblocks are each comprised of a styrofoam-type polymer in the form of a block with plug cavities. The plug cavities are generally slightly conical and are wide at the top of the block, narrowing to a small hole at the bottom of the block. The number of plug cavities is variable, as are the size and volume of the plug cavities; all are dependent upon the stock type that is being grown or the desired specifications of the final product.
The process of lifting the seedlings from the blocks in preparation for cold storage or planting is generally mechanized, although the operation is still done manually at some nurseries. Usually, the block is grasped in a holding device, a series of pins are aligned with the plugs in a row-by-row manner and the pins are pushed into the plugs pneumatically, resulting in extraction of the seedlings in their plugs. The seedlings then fall onto a moving culling bed, where they are manually checked for size and morphology, grouped into sets of seedlings and wrapped as bundles in a plastic-type film, such as Saran(trademark).
To Applicant""s knowledge, fertilization at lift has not previously been integrated into the lifting process. This, in part, reflects the difficulties in developing machinery and methodology that can be integrated into the nursery operations, and that does not damage the seedlings.
At lift, the plugs are small, soft and wet. Furthermore, they are close together, especially in the size 410 blocks (112 plugs of 80 mL), which are the most common block size used. The plugs are easily dislodged from the blocks, as the blocks are designed for easy removal of the seedlings at lift. The styroblocks must be treated with care as they are not very durable or rigid.
The preferred fertilizer for fertilizing conifer seedlings at lift is a slow-release prill or a granular type of fertilizer. The prills are fragile, as the outer coating is usually a thin, plastic polymer. The plastic coating is also hygroscopic and consequently, becomes soft and sticky in high-humidity environments. Similarly, granular fertilizer is hygroscopic and will become soft and sticky in high-humidity environments. Additionally, both granular fertilizer and prills tend to adhere to surfaces when force is applied. This makes mechanical insertion difficult as they will tend to clog the injection tubes.
The seedlings are also fragile. The aerial tissue is frequently tall, with many needles, but little branching. The root system is often quiescent at the time of lift, and therefore more susceptible to damage.
Any mechanized method of application has to accommodate the foregoing constraints.
An aspect of the present invention is a drill/injector combination that delivers various plant growth modulators (e.g. fertilizer, pesticide etc.) to a plug at lift. Lift may occur prior to transplanting, as occurs in a transplant nursery, or prior to cold storage, or prior to outplanting. In each case, injection of plant growth modulators into the interior of the plug from the plug""s top surface, as contrasted with deposit of such material onto the surface of the plug, could result in perturbation of the seedling.
Examination of seedling morphology indicates that there are a large number of crown roots at the top of the plug. In addition, the location of the stem is variable in the plug and the seedling has substantial aerial tissue. These factors may make it difficult to inject fertilizer into the top of the plug, as damage to the any part of the plant including the root system, stem or aerial tissue could reduce outplanting success, measured as survival and growth in the first few years following outplanting. Consequently, injection is preferably into the bottom of the plug. The present invention provides an apparatus for injection of the plant growth modulator into the bottom of the plug, preferably by pneumatically injecting the plant growth modulator into the plug.
As mentioned above, the hole at the bottom of the plug is small. This places a size constraint on the injection equipment.
For injection into the bottom of the plug, the blocks are preferentially placed on their sides. This promotes retention of a specific dose of fertilizer; if the blocks are upright and the plugs are injected from below, the fertilizer tends to fall out of the plugxe2x80x94even when all the operations are performed with the seedlings on their side there is loss of fertilizer. Further, more air pressure and a higher air flow would be required to inject from below as compared with injecting from the side. As a consequence, the seedlings should be supported, as they may bend and be damaged if left unsupported.
In order to successfully inject plant growth modulator into the plug, it is preferable to pre-form a bore and a port in the plug. The bore is preferably formed by drilling with a cavity drilling tool which is comprised of a specially formed drill bit and a suitable drive. Drilling is preferably through the bottom of the plug. As the drill bit reaches the end of its stroke, a distal tip of the drill bit penetrates a top end of the plug and produces the port. The port allows air to be expelled from the bore. By having a shoulder on the drill bit between a wide cylindrical body and a narrow distal tip, a shoulder is created within the bore. The narrowing of the bore afforded by the shoulder impedes movement of the plant growth modulator from the bore into the port. Further, the smaller diameter of the narrow distal tip and its flexibility reduces the risk of damage by the drill bit to the seedling.
In order to optimize the injection procedure, the charge (dose) of plant growth modulator injected into each plug should be controlled. Assuming that a metering system of the sort disclosed in U.S. Pat. No. 5,189,965 is used, the correct dose can be applied by selecting the appropriate metering roller, which forms part of the metering roller apparatus. Each metering roller has pockets sized to deliver a specific amount of plant growth modulator, and different rollers have different pocket sizes. Once the dose has been determined, the appropriate metering roller is used to deliver plant growth modulator to the to the individual injectors, which deliver the charge to the plug. This is preferably accomplished with a pneumatic injection system.
Once the plug has been injected, it is preferable to close the bore at the bottom of the plug. This can be accomplished with a bore closer or a paste injector. Closing the bore facilitates retention of the plant growth modulator in the bore.
Preferably, drilling occurs in at least one self-contained set of plugs, while at the same time injection is occurring in at least one adjacent self-contained set of plugs, while bore closing is occurring in yet another self-contained set of plugs. The sets are then laterally displaced so that the drilled set is positioned for injection, the injected set are positioned for closing, the closed set removed, and a fresh set is positioned in place for drilling, thereby minimizing the time required to drill, inject and close a series of such plug sets. The xe2x80x9csetxe2x80x9d of plugs may conveniently be a row of plugs in a block, or in a more expensive facility, could be an entire block of plugs, provided that the plugs may be maintained in satisfactory alignment for the drilling and injection operations. Accordingly, it is preferable to align and then restrain the block during drilling. An indexing bar is employed to align the various tools with the plugs, and a clamp holds both a block restraint and a seedling holder in place.
The seedling holder reduces damage to the aerial tissue of the seedlings, by supporting and holding them in one place during the drilling, injecting and closing operations. Preferably, the seedling holder is comprised of a series of guides spaced to accept a row of seedlings, that slide between the row and support the aerial tissue of the seedlings. More preferably, the seedling holder has a series of dividers. The dividers are biased from the guides in an open position to allow the seedling to slide into place, and then close onto the guides in the closed position to hold the seedlings.
In the preferred embodiment of the invention, the operations are automated, and may, for example, be controlled by a timer, a micro-controller or a microprocessor.
In one embodiment of the invention, a drill bit is provided for preparing a plug for subsequent injection of plant growth modulator into the plug. The drill bit has a distal end, a body and a shoulder between the distal end and the body. A bore is created in the plug by the drill bit by rotating the tool with a suitable drive. Exit of the distal end of the drill bit through the top of the plug results in the formation of a port for release of air during injection of the plant growth modulator into the bore. The drill bit is preferably comprised of a malleable metal such as aluminum.
In another embodiment of the invention, a cavity drilling apparatus is provided, which comprises a series of drill bits that are rotationally mounted along a head and spaced in order to align with the plugs of the container. At least one coaxially mounted bearing locates the drill bits in the head. The drill bits are coupled to a suitable drive.
In one embodiment of the invention, a metering apparatus is provided, comprising a metering roller, at least two bolts and a perforated cover. The metering roller has a series of pockets, sized to accept a specific and predetermined amount of plant growth modulator. Rotation of the metering roller from a first position, wherein the pockets accept plant growth modulator, to a second position, wherein the pockets are aligned with perforations in the perforation plate results in plant growth modulator being delivered in specific and predetermined doses. The metering roller is rotatably mounted on the perforation plate by at least one bolt at one end and at least one bolt at the opposing end. The metering roller is preferably comprised of a high density plastic polymer. Preferably, the metering roller further comprises a flap. The flap extends the length of the metering roller and rests on the metering roller.
In a preferred embodiment of the invention, the metering roller preferably subtends a hopper.
In one embodiment of the invention, an injector is provided to inject plant growth modulator into a plug. The injector is comprised of a pneumatic injection tube, a propellant port, a charge collection chamber and a nozzle. The collection chamber is located between the propellant port and the nozzle and is proximal to the metering apparatus. Plant growth modulator that collects in the collection chamber is forced into the plug in a discrete charge. Preferably, the plant growth modulator is air-entrained.
In another embodiment of the invention, an injection apparatus is provided, which comprises a series of injectors that are positioned on a head. The injectors are spaced in order to align with the plugs of the container during injection of the bores.
In another embodiment of the invention, a bore closing tool is provided.
In another embodiment of the invention, a bore closing apparatus is provided, which comprises a series of bore closers that are positioned on a head and are spaced in order to align with the plugs of the container during closing of the bores. Preferably, the bore closer has a paddle located on a distal end.
In an alternate embodiment of the invention, a paste extruder is provided.
In yet another aspect of the invention, a series of paste extruders are positioned on a head and are spaced in order to align with the plugs of the container during closing of the bores.
In another embodiment of the invention, there is a hydraulic injector, wherein the propellant port is replaced with a hydraulic tube which has, at a distal end, a hydraulic ram. Actuation of the hydraulic ram forces air through the pneumatic injection tube, entraining the plant growth modulator in the collection chamber, and releasing it through the nozzle.
In another embodiment of the invention, the hydraulic injector is controlled by, for example, a microprocessor, such that pulses of air are delivered to the pneumatic injection tube. Each pulse of air results in delivery of one charge of plant growth modulator. After each pulse, the collection chamber is reloaded with plant growth modulator.
In another embodiment of the invention, there is a hydraulic injection apparatus, which comprises a series of injectors that are positioned on a head and are spaced in order to align with the plugs of the container during injection of the bores.
In yet another embodiment of the invention, there is a fluid injector, comprising a fluid delivery tube, a collection chamber, a fluid injection tube and a nozzle. A pump injects fluid into the fluid injection tube from the fluid delivery tube, thereby fluid-entraining the plant growth modulator in the collection chamber, and releasing it through the nozzle.
In yet another embodiment of the invention, there is a fluid injection apparatus, which comprises a series of injectors that are positioned on a head and are spaced in order to align with the plugs of the container during injection of the bores.
In another embodiment of the invention, the fluid injector is controlled by, for example, a microprocessor, such that pulses of fluid are delivered to the fluid injection tube. Each pulse of fluid results in delivery of one charge of plant growth modulator. After each pulse, the collection chamber is reloaded with plant growth modulator.
In another embodiment of the invention there is a seedling holder comprising a framework and a series of guides and dividers. The guides are aligned to separate the seedlings into rows. Each row of seedlings is then retained by the dividers, which are articulated and can close over the seedlings.
In another aspect of the invention, a clamp clamps the seedling holder to the block restraint.
In one embodiment of the invention, there is an injection slide upon which are housed a cavity drilling apparatus, an injection apparatus and a bore closing apparatus.
In a preferred embodiment of the invention, the injection slide is further provided with a positioning dowel.
In one embodiment of the invention, there is a cavity tool and an injector. The cavity tool is comprised of a drill bit that is coupled to a suitable selected drive.
In another aspect of the invention, there is a cavity tool, an injector and a bore closing tool.
In another aspect of the invention, there is a cavity tool, an injector and a metering apparatus.
In another aspect of the invention, there is a cavity tool, an injector, a metering apparatus and a bore closing tool.
In another aspect of the invention, there is a cavity drilling apparatus and an injection apparatus.
In another aspect of the invention, there is a cavity drilling apparatus, an injection apparatus and a bore closing apparatus.
In another aspect of the invention there is a cavity drilling apparatus, an injection apparatus and a metering apparatus.
In another aspect of the invention there is a cavity drilling apparatus, an injection apparatus, a metering apparatus and a bore closing apparatus.
In another aspect of the invention there is a block restraint and an injection apparatus.
In another aspect of the invention there is a block restraint, a cavity drilling apparatus and an injection apparatus.
In another aspect of the invention, there is a block restraint, a cavity drilling apparatus, an injection apparatus and a metering apparatus.
In another aspect of the invention there is a block restraint, a cavity drilling apparatus, an injection apparatus and a bore closing apparatus.
In another aspect of the invention there is a block restraint, a cavity drilling apparatus, a metering apparatus, an injection apparatus and a bore closing apparatus.
In another aspect of the invention there is a seedling holder and an injection apparatus.
In another aspect of the invention there is a seedling holder, a cavity drilling apparatus and an injection apparatus.
In another aspect of the invention there is a seedling holder, a cavity drilling apparatus, a metering apparatus and an injection apparatus.
In another aspect of the invention there is a seedling holder, a cavity drilling apparatus, an injection apparatus and a bore closing apparatus.
In another aspect of the invention there is a seedlings holder, a cavity drilling apparatus, an injection apparatus, a metering apparatus and a bore closing apparatus.
In another aspect of the invention, there is a block restraint, a seedling holder and an injection apparatus.
In another aspect of the invention there is a block restraint, a seedling holder, a cavity drilling apparatus and an injection apparatus.
In another aspect of the invention there is a block restraint, a seedling holder, a cavity drilling apparatus, a metering roller and an injection apparatus.
In another aspect of the invention there is a block restraint, a seedling holder, a cavity drilling apparatus, an injection apparatus and a bore closing apparatus.
In another aspect of the invention there is a block restraint, a seedling holder, a cavity drilling apparatus, a metering apparatus, an injection apparatus and a bore closing apparatus.